Stereo depth cameras are well-known and are often used to measure a distance from an object. One such measurement device includes a projector and a camera. In such a device, the projector projects a more or less random pattern image on an object (e.g., a scene), and an image of the object upon which the image is projected is captured by the camera. From the captured images, depth information may be determined. One technique for determining depth in such devices is through the use of triangulation. Thus, images of objects are captured and measurements are taken to determine depth information.
There is need to calibrate the relationship of intrinsic and extrinsic geometric parameters of an active coded light passive triangulation. Typically, the process is performed once on a per-unit basis during the assembly process. However, the ability to properly determine the position of objects captured by stereo depth camera systems is sensitive to micron levels of relative movement between an IR projector, IR camera, and RGB camera. This means a stereo depth camera system may lose calibration after the initial calibration due to temperature changes, after a user has dropped the system causing relative movements of one or more components, when the system has been bent, etc.
For the stereo depth camera system to be recalibrated, after one or more of the events discussed above, a special chart is presented to the camera system, images of the special chart captured, and the new calibration values obtained. Thus, recalibration may be difficult, impractical, or overly time consuming when a user of the system does not have the reference chart, or must generate the special chart in order to perform the recalibration.